This invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus for examination of a coeliac cavity.
The scanning process of an ultrasonic diagnostic apparatus for examination of a coeliac cavity is generally carried out electronically or mechanically. With an electronic scanning type ultrasonic diagnostic apparatus, a large electronic scanning type ultrasonic transducer is set near the distal end of the insertion section of said diagnostic apparatus, thereby undesirably widening its thickness in the proximity of the distal end of the insertion section. With a mechanical scanning type ultrasonic diagnostic apparatus, a relatively large rotation power source section can be set in the operation section, making it unnecessary to use a thick insertion section. However, the mechanical scanning type ultrasonic diagnostic apparatus has the following drawbacks. It is necessary to use a rotation torque-transmitting wire for the rotation of an ultrasonic transducer or ultrasonic reflection mirror provided in the proximity of the distal end of the insertion section. This rotation torque-transmitting wire is conducted through the elongate insertion section to transmit the rotation torque of the rotation power source to the transducer or mirror. A scanning mechanism containing the transducer or mirror is received in a chamber filled with a liquid ultrasonic transmission medium. The opening of the distal end of the rotation torque-transmitting wire passage is sealed in a liquid-tight state in order to prevent said liquid ultrasonic transmission medium from leaking to the operation section through said rotation torque-transmitting wire passage. Therefore, the rotation torque-transmitting wire undergoes resistance resulting from friction with the sealed section. The rotation member, such as a mirror is rotated in the liquid ultrasonic transmission medium, thereby imposing a considerable twisting force on the rotation torque-transmitting wire. Therefore, said wire fails to properly transmit the rotation torque. The flexible wire passing through the flexible insertion section readily tends to be twisted. Therefore, when the rotation torque must be properly transmitted, then it is necessary to use a thick rotation torque-transmitting wire. This unavoidably causes the insertion section to be formed relatively thick, thereby undesirably imparting great pain to an examinee.